Sound recording system



March 18, 1941. A. c. BLANEY 2,235,513

SOUND RECORDING SYSTEM Filed Aug. 5, 1939 7 Sla/VAL Sol/ece Afan/ue C.JLANEY? www Patented Mar. 1,8, 1941 UNITED STATES SOUND RECORDING SYSTEMArthur C. Blaney, Los Angeles, Calif., assignor to Radio Corporation ofAmerica, a corporation of Delaware Application August 5., 1939, SerialNo. 288,613

14 Claims.

This .invention relates to sound recording systems :and particularly tothe recording of sound -on motion picture film.

It is the gener-al practice in motion picture studios to record sound inrelated and unrelated sequences which are spliced .together at the endof the day and processed. The 'picture sequences `are also photographedand treated in the same manner. The sound and picture negatives are-then printed individually .but reproduced in synchronism for inspectionthe neX-t day. Certain sequences or sections of sequences are marked for`deletion at this inspection, while subsequent editing eliminates landinterchanges other picture 15 and sound sequences to form the storycontinuity. For this purpose one or more sound prints from the originalnegative may be made and used.

When the nal cutting or editing has been completed, the originalnegative is then cut to con- .20 form with the fin-al edited print, fromwhich original negative anew print is made for -rerecording purposes.The rerecording step produces the nal negative from which thecombination picture and sound print is made for release to the 525theatres. An individual sound print may, sometimes, however, be used in-theatres for preview showings. It is realized from the above thatseveral printings and several processings are required before the nalprint is produced, each l :30 step providing the opportunity for, andgenerally, introducing some distortion and noise.

Sound motion picture studios are, however, aware of a type of soundrecording system known as the reverse negative or direct positive sys-35 tem, such as disclosed and claimed in copending iapplication SerialNo. 168,173, led October 9, 1937. This system produces a positive recordby the original recording and one which is suitable for reproduction,thus eliminating the necessity Ll0 of a printing step and a print.Although this system has many advantages, such as being a much quietersound track from the ground n-oise standpoint, it is general practice tomake a negative therefrom in order .to obtain additional prints 45 forediting and inspection purposes. However,

the direct positive system does provide an immediate record after oneprocessing step which may be used for the rst daily inspection and isparticularly good for rerecording purposes. 50 The present invention isdirected to a recording system which provides on .the same iilm both adirect positive record which may be immediately reproduced and also -anegative record of the same sounds on the same film strip, identical 55portions of the sounds'belng opposite one an- This double trackrecording system is now used Y as follows: Although the direct positivetrack may be reproduced for inspection and sometimes is, prints are madefrom the negative track only, these prints being used for inspection andediting. The double track nlm is then cut according to an edited print,which automatically cuts both lthe negative and direct positive tracks.NOW instead of havin-g I to make another print from the negative forrerecording purposes, the cut direct positive may be employed forrerecording, this track being not only superior by being more quiet thana print made from the negative, but it saves the time and cost of makinga rerecording print. It also sometimes occurs that a preview is givenwherein the picture is projected from one lm and the sound is reproducedfrom a separate sound nlm. The quiet direct positive Amay be used forthis purpose.

Also, certain types of sound tracks, such as push-pull tracks requiringspecial reproducing apparatus not in general use in theatres, have beenfoundadvantageous for the original recording in the studios where suchspecial reproducers are available. Thus, this type of sound track isused for the direct positive for use in the studio, while the adjoiningnegative track may be of the standard form for universal use, althoughit may also be of the push-pull type for studio use.

The principal object of the invention, therefore, is to facilitate soundrecording in the production of motion pictures.

Another object of the invention is to simultaneously record one type ofsound track adjacent 'and opposite a second type of sound Itrack on theAportion of the lm.

Although the novel features which are believed to be characteristic ofthis invention are pointed out with particularity in the claims appendedherewith, the manner of its organization and the mode of its operationWill be better understood by referring to the following description readin conjunction with the accompanying drawing forming a pant thereof inwhich- Figure i is a diagrammatic View of a recording system embodyingthe invention; land Figure 2 is a lm representing the type of soundtracks produced with the system of Fig. 1.

Referring now to Fig. 1, a pair of light sources represented byfilaments 5 and 6 produce light which is collected by respectivecondenser lenses 8 and 9 for projection through respective masks i iland II.. The light through the mask I0 passes a pair of noise reductionshutters I3 under control of a solenoid i4 connected in the standardmanner to a noise reduction unit as disclosed and claimed in U. S.Patents 2,102,776; 2,102,777; and 2,102,773. The light passing the maskI0 is projected on a galvanometer mirror IB having an actuating coil ilconnected to a signal source as shown in the above-mentioned patents.

The light passing the mask I0 and shutters I3 and striking the mirrorI'I is projected on a slit mask 20 having a slit 2l therein, the lightbeam at times of no signal being shown by shaded area 22 on the mask 20.The light passing the slit 2I is projected on sound track area 26 of aIilm 24 by projection lenses 25.

The light passing through mask II is also projected upon thegalvanorneter mirror I6 and then reflected to a slit mask 2 having aslit 28 therein, the light beam at times of no signal being representedby the shaded areas 30. The light passing the slit 28 is projected onsound track area 32 of the film 2li by projection lenses 3|.

The type of aperture in mask I0, noise reduction shutters i3, and theVibration of mirror I6 produce a standard duplex bilateral variable areasound track, while the mask I I with its solid portions 34 and 35 andthe Vibration of mirror I6 produce a push-pull class-B sound track ofthe direct positive type, as disclosed and claimed in theabove-mentioned copending application. Referring to Fig. 2, the standardduplex track is shown along the left-hand side of the iilm and comprisesopaque Zero signal lines 31, a single frequency modulation 38 forpurposes of illustration, and bias shutter traces 39, the darkened areasbeing the opaque portions of the film and the other portions beingtransparent. This is a negative track and, in printing, the opaque andtransparent areas are reversed to produce the normal positive antigroundnoise sound record. On the right-hand side of the film 24, the modulatedareas 4I and zero lines 42 are transparent and the remaining areas 43are opaque, thus representing a positive sound track record of theclass-B type.

The sound track 32 is immediately reproducible, while the negative 26must be printed to produce the usual type of commercial print. The track32 is also quieter than a printed track made from the negative 2S andthus is superior for reproduction and rerecording purposes. It requires,of course, a reproducer with the pushpull type of reproducing elementsand circuit, but this equipment is available in motion picture studios.The prints made from the track 26, on the other hand, are reproduciblein all standard equipment and may be used universally. This method ofrecording, therefore, provides a higher quality iinal print since iteliminates a printing step and a processing step and utilizes aYpreferred form of original recording for rerecording. Itcorrespondingly reduces time and expense.

It is to be understood that the forms of the simultaneously made tracksmay be varied or changed without departing from the spirit of theinvention. For instance, both tracks may be of the push-pull type sinceboth are reproduced for inspection or rerecording purposes on studioequipment, the rerecorded negative, however, being of the presentstandard type for release.

I claim as my invention:

1. The method of sound recording comprising simultaneously recording anegative record and a direct positive record on the same iilm of thesame sound Waves.

2. The method sound recording in accordance with claim 1 in which saidnegative record has a type of sound track different from that of saiddirect positive.

3. The method of sound recording comprising simultaneously making a,direct positive record and a negative record of sound waves, printingediting prints from said negative record, and rerecording from saiddirect positive record to produce a iinal release print negative.

4. The method of sound recording comprising simultaneously making anegative record and a direct positive record of sound waves, printingediting prints from lsaid negative, rerecording said directpositiverecord to a second negative record, and printing release printsfrom said second negative record.

5. A sound film comprising a negative sound record and a direct positivesound record of the same sound waves on the same nlm.

6. A sound film in accordance with claim 5 in which said negative recordhas a track of a type diierent from that of said direct positive.

7. A sound film in accordance with claim 5 in which the same sounds ineach record are oppositely disposed transversely of said film.

8. A sound nlm in accordance with claim 5 in which one of said recordsis a standard type of sound track and the other of said records is apush-pull type of track.

9. The method of sound recording comprising simultaneously making adirect positive record and a negative record of sound Waves, making aprint from said negative record, editing said print, cutting saidnegative record and said direct positive record to conform to saidedited print, and rerecording said direct positive record to a secondnegative record.

10. The method of sound recording in accordance with claim 9 in whichsaid second negative record is printed to make release prints.

11. A sound recording system comprising means for recording sound Wavesas a negative sound record upon a iilrn, and means for simultaneouslyrecording said sound waves as a direct positive sound record on saidsame lrn oppositely disposed from said first record transversely of saidlm.

12. A sound recording system comprising means for recording sound wavesas a negative sound record, and means for simultaneously recording saidsound waves as a direct positive sound record, both of Said meansincluding a. common element for recording on the same iilm, said elementbeing a light beam modulator upon which said sound waves are impressed.

13. A sound recording system comprising a plurality of light sources, apluralityof respective `optical units for projecting light from lsaidlight sources to anim, a plurality of respective masksl for determiningthe type of sound track to be recorded by each of said units, and alight beam modulator common to said light sources, optical units andmasks for simultaneously recording sound waves impressed on saidmodulator, one respective light source, optical unit and mask producinga negative sound record, and another respective light source, opticalunit and mask producing a direct positive sound record.

14. A sound recording system for recording the same sound waves in aplurality of sound record tracks upon the same nlm, comprising aplurality of individual recording units for producing said tracks onsaid lm, one of said units producing a negative sound record 'andanother of said units producing a direct positive sound record, and alight modulator common to all of said recording units and upon whichsaid sound waves are impressed as electrical currents substantiallycorresponding in frequency and amplitude to said sound waves.

ARTHUR C. BLANEY.

